aljabr (faa335) – Hw27 – Ross – (89251)
1
This
printout
should
have
11
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
001
10.0 points
Pure helium gas is admitted into a tank con
taining a movable piston.
The initial vol
ume, pressure, and temperature of the gas are
0
.
047 m
3
, 197 kPa, and 421 K.
If the volume is decreased to 0
.
011 m
3
and
the pressure is increased to 480 kPa, find the
final temperature of the gas.
Correct answer: 240
.
078 K.
Explanation:
Given :
V
i
= 0
.
047 m
3
,
P
i
= 197 kPa
,
T
i
= 421 K
,
V
f
= 0
.
011 m
3
,
and
P
f
= 480 kPa
.
If no gas escapes from the tank, the number of
moles remains constant; therefore, using the
equation
P V
=
n R T
at the initial and final points gives
P
i
V
i
T
i
=
P
f
V
f
T
f
T
f
=
P
f
V
f
T
i
P
i
V
i
=
(480 kPa)
(
0
.
011 m
3
)
(421 K)
(197 kPa ) (0
.
047 m
3
)
= 240
.
078 K
.
002
(part 1 of 2) 10.0 points
A sphere 30 cm in diameter contains an ideal
gas at 1
.
2 atm and 15
◦
C.
As the sphere is
heated to 119
◦
C, gas is allowed to escape.
The valve is closed and the sphere is placed in
an icewater bath.
How many moles of gas escape from the
sphere as it warms?
Correct answer: 0
.
190402 mol.
Explanation:
Given :
r
=
30 cm
2
= 0
.
15 m
,
P
= 1
.
2 atm
,
T
1
= 15
◦
C = 288 K
,
T
2
= 119
◦
C = 392 K
,
and
R
= 8
.
31451 J
/
K
·
mol
.
The volume of the sphere is
V
=
4
π r
3
3
=
4
π
(0
.
15 m)
3
3
= 0
.
0141372 m
3
.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '10
 Gavrine
 Correct Answer

Click to edit the document details